The present invention relates especially to an integrated avionics modular antenna system, comprising at least two directional antennas capable of working in the different frequency bands B1, B2.
It can be applied more particularly to any mobile carrier equipped with several directional antennas working, for example, in different frequency ranges and having to be located in a limited amount of space. The carrier is, for example, a ship, an aircraft, or an automobile.
In mobile applications, the antenna preferably used is the dipole antenna, practical embodiments of which include whip antennas, quarter-wave antennas and antennas integrated into portable telephones. An antenna this kind has, for example, certain disadvantages. For example it is compact for frequencies higher than 1 GHz and almost omnidirectional, i.e. it does not require any aiming device.
However, the dipole antenna also has certain drawbacks. In particular, it is a source of pollution when sending signals (it sends a signal to all the receivers in addition to the useful receiver) and is indiscriminate in reception (it receives from all the transmitters in addition to the useful transmitter). Furthermore, owing to its small size, it has low sensitivity and requires high sending power. The dipole antenna thus contributes to wastage of frequency resources. It is easier to use directional antennas in fixed applications.
Growing needs in the field of radiocommunications are leading to the deployment of several radio systems on carriers. Each system has an antenna associated with it. The concentration of the antennas and their collocation in particular gives rise to a critical drop in performance. In the case of airliners, for example, the number and the disposition of present-day antennas rules out the installation of additional antennas in practice.
Today, for mobile applications, there are, for example, reserved bands enabling the use of antennas with low directivity. This is the case with the INMARSAT system, deployed in the L band, and the future AIRTV system, deployed in the S band. The frequency resources allocated to these systems nevertheless remain marginal and their capacithy is handicapped by the low selectivity of the antennas.
The object of the invention relates to an antenna system designed to be installed, for example, on a mobile carrier. This antenna system has at least two directional antennas working in different frequency domains.
The antenna system carries out the function of several antennas, for example the function of three directional antennas, in a volume and with ancillaries equivalent to those commonly needed for an antenna.
The object of the invention relates to an antenna system comprising at least three directional type antennas, a Gatelink antenna, a Satcom Ku antenna and a Satcom Inmarsat antenna, said antennas being positioned on a support that is mobile in rotation and/or in translation and a device for the protection of the antennas.
The antennas are protected, for example, by a radome.
It may furthermore comprise a GPS type antenna.
The invention also relates to a telecommunications system comprising at least one antenna system having one of the above-mentioned characteristics and at least one antenna-aiming device, linked with an inertial guidance unit as well as a transceiver.
The invention is used, for example, to equip the fuselage of an airliner.
The antenna system that is the object of the present invention offers especially the advantage of integrating several directional antennas in a small-sized system.